SQLServer 2005 Installation

Hello. I was wondering if you can help me out. We got a new server and it has Windows Server 2003 Standard Edition as the O/S. I was trying to install SQL Server 2005 this morning and I keep getting this “not a valid Win32 application” error message. The necessary SP has been installed on the server. I read somewhere that it’s “impossible” to install SQLServer 2005 on WinServer 2003. Is this true? If not true, can anybody tell me what I’m doing wrong, or if I’m forgetting something? Your inputs are greatly apprciated. Thanks